The present invention relates to a device for interconnecting two sections of a longwall mining machine track secured to the side wall of a face conveyor. Lugs project outwardly from the sides of adjacent end portions of the respective track sections and receive an oval chain link element which extends around the lugs and bridges the joint between the respective track sections.
A device of the general type described above for interconnecting sections of a longwall mining machine track is shown in U.S. Pat. No. 4,265,488. That patent discloses a longwall mining machine track on which the discrete sections of the track have coupling plates disposed on their opposite ends. Projecting outwardly from each coupling plate is a lug over which a chain link coupling element is pushed, the coupling element extending around and providing an articulated connection between the discrete track sections.
In addition to interconnecting discrete sections of a track which are disposed on the face side of a longwall face conveyor, similar chain link coupling elements serve to retain the side bracket portions secured to the opposite side of the face conveyor. These chain link elements are the only elements which determine the play or slack in the face conveyor between adjacent track portions. In the case where the machine track or a side bracket has a toothed rack to advance the longwall mining machine, the clearance between the track sections always must be such that the pitch of the rack teeth at the joints between adjacent track sections can vary only within permissible limits in order to facilitate engagement of the teeth of the mining machine drive wheel with the rack at the joints.
After a longwall mining machine traverses the face area being mined and removes material therefrom, the conveyor on which it travels must be pushed or advanced toward the face for the next cutting operation. The chain link connecting elements for the discrete track sections, as well as the side bracket sections, are heavily loaded during conveyor advance, not only by transverse forces exerted in the direction of the advance but to the same extent by tensile force which act lengthwise of the face conveyor and which are produced by the advancing movement. These forces reach orders or magnitude which are sufficient to cause permanent elongation of the connecting elements, thus increasing the clearance excessively between adjacent track or side bracket sections. In the extreme case (i.e., curved portions of the face conveyor as it is advanced toward the face), the clearance between adjacent sections of track or side bracket may increase to such an extent over a period of time as to exceed the desired tooth pitch between track sections and impair engagement of the driving wheel of the mining machine with the rack.